JPH02124996A - Method for heating high-temperature carbonization gas in continuous coking installation - Google Patents

Abstract

PURPOSE:To make it possible to continuously feed a high-temperature carbonization gas at a constant temperature into a continuous carbonization shaft oven by a process wherein a circulating gas is primarily heated, and a combustible component therein is then burned to raise the temperature of the gas to thereby from a high-temperature carbonization gas. CONSTITUTION:A circulating gas 14, discharged from a continuous carbonization shaft oven 3 of a continuous coking installation and flowing through a high- temperature gas pipe 15, is primarily heated at 500 deg.C or higher in an indirect heat exchange 27. An oxygen-containing gas 29 at 500 deg.C or higher is blown at a prescribed flow rate through an oxygen introducing pipe 28 into the heated circulating gas 14 to burn 10% or less of the combustible component therein to raise the temperature of the circulating gas, thus forming a high-temperature carbonization gas 4. The gas 4 is then fed into the oven 3.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a method for producing metallurgical shaped coke by carbonizing briquettes using an upright carbonization furnace using combustible gas as a heat carrier. The present invention relates to a method of heating high-temperature carbonization gas.

[Conventional technology]

Molded coke production involves adding a binder (caking agent) to coking coal, the main raw material of which is steam coal, pressurizing and shaping it to create briquette coal, which is then fed into an upright continuous carbonization furnace to produce metallurgical coke. The equipment is ``Fuel Temperature Journal'' Vol. 61 No. 659 No. 1
pp. 69-178, "Steel World" August 1980 issue No. 115
It is introduced on pages 121 to 121.

FIG. 6 shows the equipment flow of this molded coke manufacturing equipment. Molten coal 2 produced in coal briquette manufacturing equipment 1 is charged into an upright continuous carbonization furnace 3 from the top thereof. This vertical continuous carbonization furnace 3 has a two-stage gas blowing structure in which high-temperature carbonization gas 4 is introduced from the lower part and low-temperature carbonization gas 5 is introduced from the middle part. Molded coal 2 charged from the top of the furnace is heated and carbonized at an appropriate rate by low-temperature carbonization gas 5 and then by high-temperature carbonization gas 4. The obtained coke descends to the cooling zone at the bottom of the vertical continuous carbonization furnace 3, is cooled to about 130° C. by cold gas 6 blown from the bottom, and is then cut out from the discharge device 7 as carbonization coke 8.

The high-temperature carbonized gas 4 and the low-temperature carbonized gas 5 used as a heat medium for heating the coal briquettes 2 are flammable COG generated as a by-product during the production of shaped coke. That is, the gas generated by carbonization of the coal briquette 2 rises in the upright continuous carbonization furnace 3 together with the high-temperature carbonization gas 4 and low-temperature carbonization gas 5 blown into the furnace, and passes through the sensible heat recovery device 9 from the top of the furnace. and sent to the dust collector 11 via the gas cooler 10. After dust removal by the collector 11, a part of the generated gas is sent as a recovered gas 12 to a by-product recovery facility 13, where it is used as COG fuel after being purified and desulfurized.

Most of the remaining generated gas is sent as circulating gas 14 to the gas circulation facility. This gas circulation equipment has a circulating gas 14
t1 high-temperature gas piping 15. It is equipped with a low temperature gas pipe 16 and a cold gas pipe 17. A gas heater 18 is provided in the high-temperature gas pipe 15, and the circulating gas 14 is heated to a predetermined temperature and blown into the vertical continuous carbonization furnace 3 as a high-temperature carbonization gas 4. On the other hand, the low temperature gas pipe 16 is provided with a heat exchanger 19 and an ejector 20, and after adjusting the temperature of the circulating gas 14, the low temperature carbonized gas 5 of 600 to 650°C is
It is blown into the vertical continuous carbonization furnace 3.

As the gas heater 18, as shown in FIG. 7, one having a structure similar to that of an external combustion hot blast furnace, which is one type of blast furnace equipment, is used. That is, the gas heater 18 is one combustion furnace 21. Two heat storage furnaces 22a, 22b.

It is composed of switching valves 23a to 23h and various types of piping connecting these. In the combustion furnace 21, mixed gas is constantly combusted, and the combustion exhaust gas is supplied to either the regenerative furnace 22a or 22b by switching the switching valve 23C or 23d.

For example, by opening the switching valve 23c and closing the switching valve 23d,
When the combustion exhaust gas is being sent to the regenerative furnace 22a, its retained heat is given to the regenerative bricks of the regenerative furnace 22a. Then, the exhaust gas whose temperature has decreased to about 300° C. is dissipated from the chimney 25 via the exhaust gas conduit 24. At this time, the circulating gas 14 is introduced into the other regenerator 22b from the cold gas pipe 26 via the switching valve 23h. This circulation gas 14 receives heat from the heat storage bricks of the heat storage furnace 22b, raises the temperature to a high temperature of approximately 950°C, and converts the high-temperature carbonization gas 4 into the upright continuous carbonization furnace 3.
is supplied to

After a predetermined period of time has elapsed, the switching valves 23a to 23h are switched, and the circulating gas 14 is introduced into the regenerator 22a to raise its temperature, and in the regenerator 22b, the combustion exhaust gas from the combustion furnace 21 raises the temperature of the regenerator bricks. In this way, the switching valves 23a to 23h
By switching the regenerative furnaces 22a and 22b to about 30
The heat storage period and the ventilation period are switched at intervals of about minutes to obtain high-temperature carbonized gas 4 heated to a predetermined temperature.

[Problem to be solved by the invention]

When the gas heater 18 is used to heat the circulating gas 14, the temperature of the resulting hot carbonized gas 4 is not constant. That is, at the initial stage of switching the regenerative furnaces 22&, 22b,
Since the heat storage bricks whose temperature rose during the heat storage period retain a large amount of heat, the temperature of the obtained high-temperature carbonized gas 4 also becomes high. However, as the heat exchange between the heat storage brick and the circulating gas 14 progresses, the amount of heat held by the heat storage brick decreases, and the temperature of the high-temperature carbonized gas 4 decreases.

Fluctuations in the temperature of the high-temperature carbonization gas 4 and gas shut-off when switching over the regenerator adversely affect the furnace condition of the vertical continuous carbonization furnace 3, making it difficult to control operating conditions.

In addition, the switching valves 23a to 23h are expensive ones with special designs that have excellent heat resistance and good gas sealing properties because they come into contact with high-temperature combustion exhaust gas of approximately 1200°C and the fluid used contains flammable components. required. Furthermore, since a mistake in the opening/closing operation of these switching valves 23a to 23h may lead to a gas explosion accident, it is necessary to install a safety device, N, purge, etc. to the control equipment.

To solve this problem, the circulating gas 14
A possible method is to use an electric heater for heating. but,
In order to heat a large amount of circulating gas 14 to a high temperature, an electric heater with a large capacity is required, which increases the burden on equipment costs and operating costs. Furthermore, it is conceivable to burn part of the combustible components contained in the circulating gas 14 in the middle of the high-temperature gas piping 15 to raise the temperature of the circulating gas 14 and turn it into high-temperature carbonized gas 4 (Japanese Patent Laid-Open No. 54 -62205, JP-A-54-127903, etc.).

However, the temperature of the circulating gas 14 after exiting the dust collector 11 has fallen to near room temperature, and in order to raise the temperature of this to high-temperature carbonized gas 4 of about 900 to 950°C, it is necessary to burn a large amount of combustible components. It is. As a result, a large amount of water is contained in the high-temperature carbonization gas 4 as a combustion reaction product, which adversely affects the carbonization reaction of coal in the vertical continuous carbonization furnace 3, resulting in a deterioration in the quality of the produced coke. Moreover, since self-combustion is not sufficiently performed, high-temperature carbonized gas 4 at a predetermined temperature cannot be stably obtained, and the furnace condition becomes unstable.

Therefore, by improving the heating method for converting circulating gas into high-temperature carbonization gas, the present invention aims to continuously carbonize high-temperature gas at a constant temperature by vertical continuous carbonization without causing a rise in equipment costs, operating costs, etc. The purpose is to supply coke to the furnace and produce excellent quality coke under stable furnace conditions.

[Means to solve the problem]

In order to achieve the object, the high-temperature carbonization gas heating method of the present invention blows high-temperature carbonization gas and low-temperature carbonization gas as heating media into the lower and intermediate parts of an upright continuous carbonization furnace, respectively, and carbonizes the formed coal to form formed coke. When manufacturing, in the circulation path of the generated gas discharged from the vertical continuous carbonization furnace, after the generated gas is primarily heated to 500°C or higher with an indirect heat exchanger, the generated gas is transferred to the vertical continuous carbonization furnace. Oxygen-containing gas with a temperature of 500°C or higher is blown into the flow path immediately before it is blown into the gas, and one of the combustible components contained in the generated gas is
It is characterized in that the temperature of the generated gas is raised by burning 0% or less, and the generated gas after the temperature rise is blown into the upright continuous carbonization furnace as the high temperature carbonization gas.

[Effect]

The circulating gas 14 after exiting the dust collector 11 shown in FIG.
The temperature has dropped to near normal temperature. When the circulation raises the temperature of the gas 14 to a temperature of about 900 to 950°C required for the high-temperature carbonization gas 4 by combustion of the combustible components contained in the circulating gas 14, for example, the combustible components contained in the gas after combustion are heated. The moisture content will rise to around 15%. This water content is
It has a great influence on the strength of coke obtained by carbonization. However, the present inventors have discovered that there is an upper limit to the water content that causes a decrease in the strength of coke. This upper limit value is about 10%, although it depends on the properties of the coal briquette 2 and the target temperature of the high-temperature carbonization gas 4.

Therefore, in the present invention, by heating the circulating gas in advance with an indirect heat exchanger, the circulating gas can be heated to the temperature required for the high-temperature carbonization gas 4 (for example, 90 (1 to 150°C)). The proportion of combustible components to be burned is reduced to 10% or less.As a result, even when the target temperature is reached by self-combustion of the circulating gas 14, it is possible to suppress the moisture content to the above-mentioned upper limit of 10% or less. Therefore, even if the obtained high-temperature carbonization gas 4 is blown into the vertical continuous carbonization furnace 3, there will be no adverse effect on the furnace condition.
The coking reaction of the formed coal 2 can be maintained.

Here, the temperature of the circulating gas after the secondary heating needs to be 500°C or higher. When this temperature is 500° C. or higher, the amount of moisture contained in the high-temperature carbonized gas as a result of combustion can be suppressed to an upper limit of 10% or less at the stage of blowing oxygen-containing gas to burn the combustible components. However, if the temperature after the second heating is less than 500°C, the amount of combustible components to be burned in the next step will increase, and as a result, the moisture content in the high-temperature carbonization gas 4 will exceed 10%, causing the coal to burn out. A negative effect appears on the coking reaction.

It is also necessary to preheat the oxygen-containing gas for combustion, such as air, to 500°C or higher. This preheating promotes the diffusion between the circulating gas and the oxygen-containing gas, making the combustion reaction smooth. In addition, in order to maintain stable self-combustion, combustion is started in a relatively oxygen-rich atmosphere.For this reason, the combustion chamber is placed at a location where the ratio of oxygen-containing gas/circulating gas is 1.0 or more. An igniter is used, which facilitates the initiation of combustion of the combustible components.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 shows an upright continuous carbonization furnace and its ancillary equipment incorporating a high-temperature carbonization gas heating mechanism according to the present invention. In addition, in the figure, parts corresponding to those shown in FIG. 6 are indicated by the same reference numerals, and their explanations are omitted.

The circulating gas 14 flowing through the high-temperature gas pipe 15 is heated to a temperature of 500° C. or higher by the indirect heat exchanger 27 . As the indirect heat exchanger 27, an indirect heat exchanger such as a recuperator is used. For example, high-temperature gas is supplied to a high-temperature side pipe that is arranged so as to surround the flow path of the circulating gas 14 or in a meandering manner within the flow path, and the retained heat of the high-temperature gas is transferred to the circulating gas 14 through the pipe wall. tell.

This high-temperature gas is exhaust gas obtained by burning BFG, COG, and the like. Furthermore, since heating of the circulating gas 14 by this high-temperature gas is performed by heat conduction through the tube wall, the maximum heating temperature is about 650°C.

On the downstream side of the indirect heat exchanger 27, an oxygen gas conduit 28 opens into the hot gas pipe 15. A predetermined amount of oxygen-containing gas 29 is blown into the circulating gas 14 that has been primarily heated by the indirect heat exchanger 27 via the oxygen gas conduit 28 . The oxygen-containing gas 29 is air or pure oxygen.

Oxygen-enriched air or the like is used. This blown oxygen-containing gas 29 causes some of the combustible components contained in the circulating gas 14 to burn, and the heat of combustion raises the temperature of the circulating gas 14. At this time, in order to smoothly carry out the combustion reaction, the oxygen-containing gas 29 is heated in advance to a temperature of 500° C. or higher using a heater 30.

The opening position of the oxygen gas conduit 28 with respect to the high-temperature gas pipe 15 is determined to be close to the tuyere of the vertical continuous carbonization furnace 3. As a result, the amount of combustion heat dissipated and the high temperature gas piping 1
5. The range of soot adhesion to the inner wall can be reduced. Furthermore, although one oxygen gas conduit 28 is shown in FIG. 1, a plurality of oxygen gas conduits 28 may be opened into the high temperature gas pipe 15 without being restricted thereto.

FIG. 2 shows an example. In this example, the high-temperature gas pipe 15 is branched in correspondence with the plurality of tuyeres 3a provided in the vertical continuous carbonization furnace 3, and the oxygen gas conduit 28 is opened in each branch pipe 15a. When self-combustion is performed in the branch pipe 15a in this manner, there is no temperature drop due to heat dissipation while the high-temperature gas flows through the high-temperature gas pipe 15, and the temperature of the gas blown into the tuyere 3a is kept constant.

FIG. 3 shows the oxygen gas conduit 2 connected to the high temperature gas piping 15.
An example of the opening of No. 8 is shown. In this example, the same figure (a)
As shown in FIG. 2, an oxygen gas conduit 28 is opened in a large diameter portion 15a formed in the middle of the high temperature gas piping 15. Also,
As shown in FIGS. 3A and 3B, an oxygen gas conduit 28 is opened in the tangential direction of the large diameter portion 15a. As a result, the oxygen-containing gas 29 flowing into the large diameter portion 15a from the oxygen gas conduit 28 flows as a vortex along the inner wall of the large diameter portion 15a. On the other hand, the primary heated circulating gas 14 sent from the high-temperature gas piping 15 is diffused in the large-diameter portion 15a having a large flow path cross-sectional area. Therefore, the circulating gas 14 and the oxygen-containing gas 29 are sufficiently mixed, and combustion proceeds smoothly. Moreover, since the gas after combustion is compressed at the point where it exits from the large-diameter portion 15a, it is sent out as a high-temperature carbonized gas 4 having a uniform temperature distribution.

Here, an igniter 31 is provided at a location where the oxygen gas conduit 28 opens into the large diameter portion 15a. In this location, since the ratio of oxygen-containing gas/circulating gas is 1.0 or more, the combustible components of the circulating gas are quickly ignited. Note that the igniter 31 closes the opening of the oxygen gas conduit 28 as long as the oxygen-containing gas 29 ejected from the oxygen gas conduit 28 has not been sufficiently diffused into the exposed ring gas 14 and the oxygen-containing gas 29 is still at a high position. It can be provided near the section.

FIG. 4 shows the flow rate of the oxygen-containing gas 29 supplied from the oxygen gas conduit 28 to the high temperature gas pipe 15, and the flow rate of the high temperature carbonized gas 4.
FIG. 3 is a diagram illustrating an example of a mechanism for controlling based on a target temperature.

An orifice 32 is provided in the middle of the oxygen gas conduit 28, and a differential pressure oscillator 33 detects the pressure difference in the oxygen-containing gas 29 flowing through the oxygen gas conduit 28 before and after the orifice 32, and sends it to a flow meter 34. The flow rate of gas 29 is detected. The detected flow rate is input to the calculator 35. On the other hand, a thermometer 36 such as a thermocouple is attached to the high-temperature gas pipe 15, and a calculator 35 calculates the temperature of the high-temperature carbonized gas 4 flowing through the high-temperature gas pipe 15 detected by the thermometer 36.
is input.

The calculator 35 compares the detected temperature value from the thermometer 36 with a set value. If the detected temperature is lower than the set value, a command to open the flow rate regulating valve 37 is output to the valve opening controller 38 so as to increase the flow rate of the oxygen-containing gas 29 flowing through the oxygen gas conduit 28. As a result, combustion near the opening 28a of the oxygen gas conduit 28 is promoted, and the temperature of the high-temperature carbonized gas 4 increases. On the other hand, if the temperature detected by the thermometer 36 is high, the flow rate adjustment valve 37 is throttled and the oxygen-containing gas 29 is
This reduces the amount of gas supplied and suppresses the combustion reaction. In this way, the temperature of the high-temperature carbonization gas 4 blown into the vertical continuous carbonization furnace 3 is maintained constant. Note that an oxygen analyzer 39 is attached to the high-temperature gas pipe 15, and the oxygen content of the high-temperature carbonized gas 4 detected by the oxygen analyzer 39 is recorded on an oxygen recorder 40.

The next stage shows operating conditions when the circulating gas 14 that has passed through the dust collector 11 is heated to a high temperature carbonized gas 4 at a target temperature by primary heating and self-combustion. Note that the circulating gas 14 is 8253
%, CH4192%, CO3,7%, N219.1%,
CO23,6%, (,H,0,2%, (,2861
It is assumed that the circulating gas 14 has a composition of J%, and a necessary amount of the circulating gas 14 is sent to the indirect heat exchanger 27, where it is primarily heated. The assumption is that air preheated to 600° C. by the heater 30 is used as the oxygen-containing gas 29 for secondary heating.

(Hereinafter, the margin of this page) The injection rate in the table is expressed in Nm'/min dry, and the recovered gas calorific value is expressed in Kcal/Nm'' units.

As is clear from Table 1, when the circulating gas 14 is heated to 500°C or higher in the secondary heating, less combustion heat is generated in the next heating step, so the moisture contained in the obtained high-temperature carbonized gas 4 is reduced. The content can be suppressed to below the upper limit of 10%.

FIG. 5 is a graph showing the influence of the water content contained in the high-temperature carbonization gas 4 on the coking reaction in the vertical continuous carbonization furnace 3. As is clear from FIG. 5, as the moisture content of the high-temperature carbonization gas 4 blown into the vertical continuous carbonization furnace 3 decreases, the strength of the obtained coke increases. This tendency becomes particularly noticeable when the final carbonization temperature is increased. In this regard, in this example, since high-temperature carbonization gas 4 with a low moisture content is used, the strength of the produced coke is p 1i5Q
definitely exceeded the target value of 84.

Therefore, the proportion of pulverization during the transportation and charging of this coke into the blast furnace was small, and the blast furnace could be operated under stable conditions.

〔Effect of the invention〕

As explained above, in the present invention, the high-temperature carbonization gas blown into the vertical continuous carbonization furnace of continuous coke manufacturing equipment is generated by the combustion of combustible components after the circulating gas is primarily heated with an indirect heat exchanger. This is achieved by heating the target temperature using the heat of combustion. Therefore, the amount of combustible components consumed during secondary combustion is reduced, high-temperature carbonized gas with low moisture content is obtained, and coal can be coked without adversely affecting furnace conditions. Moreover, unlike the case of using a hot blast furnace equipped with a regenerative furnace, high-temperature carbonization gas at a constant temperature can be continuously obtained, and disturbances to the temperature distribution inside the upright continuous carbonization furnace are reduced. Also,
Because high-temperature carbonized gas at the target temperature can be obtained without the need for a hot air stove with complicated and expensive switching valves and piping, the equipment itself is simple and the burden on equipment and operating costs is reduced. Ru.

[Brief explanation of the drawing]

Fig. 1 is a flow diagram showing a continuous coke manufacturing facility incorporating a heating mechanism according to the present invention, Fig. 2 shows an example in which an oxygen gas pipe is opened in each branch pipe of a high temperature gas pipe, and Fig. The figure shows the opening state of the oxygen gas conduit to the high-temperature gas pipe, Figure 4 shows the mechanism for controlling the temperature of the high-temperature carbonization gas to the target value, and Figure 5 shows the influence of the moisture content of the high-temperature carbonization gas on coke strength. This is a graph showing the influence. On the other hand, FIG. 6 is a flowchart showing a conventional continuous coke production facility, and FIG. 7 shows a hot air oven type gas heater incorporated therein. 3; Vertical continuous carbonization furnace 4: High-temperature carbonization gas 5: Low-temperature carbonization gas 8: Carbonization coke 14: Circulating gas
27: Indirect heat exchanger 28; Oxygen gas pipe

Claims (1)

[Claims] 1. When producing molded coke by carbonizing briquette coal by blowing high-temperature carbonization gas and low-temperature carbonization gas as heating media into the lower and intermediate parts of the vertical carbonization furnace, the emissions discharged from the vertical carbonization furnace. In the gas circulation path,
After the generated gas is primarily heated to 500° C. or higher using an indirect heat exchanger, an oxygen-containing gas having a temperature of 500° C. or higher is blown into the flow path immediately before the generated gas is blown into the vertical continuous carbonization furnace. 10% of the combustible components contained in
High-temperature carbonization gas heating in continuous coke manufacturing equipment, characterized in that the temperature of the generated gas is raised by burning the following, and the generated gas after the temperature rise is blown into the vertical continuous carbonization furnace as the high-temperature carbonization gas: Method.